Hi, i'm entering deadlock when setting value with lock inside a class property

class CurrentServerTimestamp {
    private val lock: ReentrantLock = ReentrantLock()

    private var timestampInMillis: Long
        get() = lock.withLock { timestampInMillis }
        set(value) {
            lock.withLock { timestampInMillis = value }
        }

    init {
        timestampInMillis = CURRENT_SERVER_TIME_NOT_SET
    }

    companion object {

        private val instance = CurrentServerTimestamp()

        fun isValidTimeStamp(): Boolean {
            return instance.timestampInMillis != CURRENT_SERVER_TIME_NOT_SET
        }

        fun get(): Long = instance.timestampInMillis

        fun set(currentServerTimestamp: Long) {
            instance.timestampInMillis = currentServerTimestamp
        }
    }
}

set(value) {
            lock.withLock { timestampInMillis = value }
        }

I think this is causing the dead lock, is there any way to over come this and still i get the intended behavior ?

I just discovered that the Byte and Short classes (and their unsigned counterparts) have no 

shl

 or 

shr

 infix functions. Is this intentional or not?

How do I load a bitmap (or jpg or png) from file (not URL)?

hello folks.. can someone invite me to the composable channel..??

Hi folks, I’m playing with elvis(?:) operator and looking for some help, I want to return from the method when my object is null but before returning from the method I want to add a log statements, what is the correct way of doing that?

val record = (repository.findById(id) ?: (<http://log.info|log.info>("log message here") return))

What is the difference between file level: val myVariable = “const” const val myVariable = “const”

Hey guys 🙂 Was looking to do something like that but it doesn’t seem to be allowed

data class Foo(val a:Int, val b = 0)
val bar = Foo(a = 3, if(param) b = 5 /*else keep the default param */)

Is there an alternative other than

val bar = if(param) Foo(...) else Foo(...)

Hey folks, Can someone please recommend a good Android repository that showcases coroutine and flow implementations with tests?

Where can I ask somewhat off-topic thing which is not related to Kotlin Directly, Which channel is suitable for this? , as this community is quite large and I guess some people may even be happy to help/answer my query...

is there a way to choose what concrete type

associateWith

returns?

Helping an iOS coworker get ramped up into our KMP codebase. Overall things are looking great, but they mentioned that they don't quite get the point of the Kotlin StdLib Collection functional operators (map/filter/associate/etc) vs a more "standard” mutable collection + iteration I'm gonna be honest — I've been working in Kotlin for quite a while and those list operators just come naturally to me. At the same time, I don't think “because they're more idiomatic and look better (to me)” is a good enough reason. I know there are also benefits like Sequence-compatibility and ease of extracting narrowly scoped helper methods, but I'm sure there's many other reasons to use them (and situations where you shouldn't use them) that I've internalized but can't easily recall and articulate Does have a link to a good post that details the pros/cons of those operators vs the “not-kotliny” approach?

Hey. I can do `my?.chained?.call?.of?.operators?`and get null, if any of these is null. Is there a nice way of achieving the same for parameters? e.g.

fun foo(a: Type1, b: Type2, c: Type3): Type4

val result: Type4? = foo(myA?, myB?, myC?) // is null if any of the parameters is null

I need to serialize a data class I do not own. It just needs the default Serializer. Is there any easy way of doing this (hopefully without defining a custom serializer)?

If I have:

sealed interface Foo

object Bar : Foo

object Baz : Foo

fun <T : Foo> getFooObjects(): List<T> = TODO("How do I get this list?")

I want to call a method that makes an API call which is triggered by user interaction but I want to prevent it to get called multiple times if it hasn't been 1 minute yet, what would be the best way to do this?

I'm working on a Kotlin compiler plugin using arrow-meta. I'd like to know what's the official way to report compilation errors and warnings. And is there a way to have intellij handle these errors and warnings and display them?

Hi, is there any class or functions to print in color in std kotlin ?

What library would you recommend for checked exceptions? https://arrow-kt.io/docs/apidocs/arrow-core/arrow.core/-either/ or https://github.com/michaelbull/kotlin-result (or maybe others)

Why use MutableList<T> instead of ArrayList<T> in Kotlin? What was the idea standing behind the creation of that class in Kotlin when mostly the rest of the collections are used as declared in Java? If you have any docs/articles that might help me understand it, it would be very helpful. Thanks 👋🏼

With `@JvmInline value class`es existing, I’ve been wondering, is there any reason why you would explicitly not want any class you have that happens to have a single value in it’s constructor to be a

value class

? Like I see the benefits of it, but if I am creating a new data class with 1 parameter anyway, why would I not just make it a value class? Any gotchas? Couldn’t find anything in the KEEP regarding this.

I have a data class like

data class ProfileItem(val id: String, val item: Item)
data class Item (val code: String)

When I get a

List<ProfileItem>

from the 3rd service (can’t control it), the

item

field for some elements in the list might be

null

. And when I do

val eligibleCodes = service.gerProfileItems().filter { it.item.code in approvedCodes }

it fails with NPE, so I had to do

filter { it.item != null }

once I got the list. And IntelliJ complains about this filtering saying that this condition is always true. Is it an issue with the IntelliJ IDEA’s inspection? Or I should do this operation differently?

is it an anti-pattern to use sealed classes/interfaces as an approximation of an algebraic data type? i've been doing things like below, but it seems that this causes

instanceof

checks -- so naturally various stack overflow answers mentioned "code smell", and i'm wondering if there's truth to that 🙂

sealed class Node

data class Leaf(x: Int): Node()
data class Tree(left: Node, right: Node?): Node()

Hello everyone! I would want to know what options do I have if I want something like a Min/Max Heap or Priority Queue in Kotlin. I look in the docs but didn't find anything 😞

Sealed interface serialisation seem to be broken unless explicitly registered. Am I missing something?

import kotlinx.serialization.*
import kotlinx.serialization.json.Json
import kotlin.test.Test

sealed interface iFoo {
    @Serializable
    @SerialName("a")
    class A() : iFoo//Foo(),
}

class EventTest {
    @Test
    fun testKotlinLang() {
//        // this works
//        val json = Json { serializersModule = SerializersModule {
//                polymorphic(iFoo::class) {
//                    subclass(iFoo.A::class, iFoo.A.serializer())
//                } } }

        val json = Json

        val a = iFoo.A() as iFoo
        val s = json.encodeToString(a)
        val a1: iFoo = json.decodeFromString(s)
    }
}

Guys I am new at Kotlin, can you guys tell me where I am getting wrong?

Given an expression

someCollection.take(42).forEach { /* ... */ }

is there a way to access the collection inside the forEach that the forEach is iterating over?

Data modeling question: I'm trying to essentially model 5 different csv files that have a few common fields as Kotlin objects that are going to be displayed and edited in lists. So like page 1 would be identifier, time, last_update, location name, color. Page 2 would be identifier, time, last_update, activity_type, length, etc, with all of them having identifier, time, and last_update in common. In my Android app's UI, these will all be displayed in a list, by time. Is there a gotcha that makes sealed classes a bad move for this data modeling situation?

Hi👋, Can someone tell me why the compile error is going away as soon as uncomment the

student as Student

from the below code? Don’t I have to explicitly assign the cast result to a variable to access the

score

property?

abstract class Person(val name: String)
class Student(val score: Int, name: String) : Person(name)
class Teacher(name: String) : Person(name)

fun someFun(student: Person) {
//  student as Student
    
    println(student.score)
}

Isn't there any plan to replace Gradle? If you want reasons just Google it.